Synthesis of hierarchical ZSM‐5 microspheres with superior performance for catalytic methanol‐to‐olefin conversion

Abstract

Methanol-to-olefin (MTO) conversion on zeolites has encountered severe coke deposition and rapid deactivation. Creating different levels of porosity is essential to mitigate such issues. Herein, we demonstrate a facile and green strategy to synthesize uniform and hierarchically macro/mesoporous ZSM-5 microspheres by combining spray-freeze drying and steaming-assisted crystallization (SAC). The structure, crystallinity, and porosity of the zeolite microspheres are controlled by adjusting the water/gel mass ratio and time in the SAC process. The structure evolution during the SAC process is revealed. In the catalytic MTO reaction, the representative hierarchically porous ZSM-5 catalyst exhibits superior catalytic performance. At a very high weight hourly space velocity of 18 h À1 , it shows a dramatically prolonged lifetime (47 h at >99% conversion) and much-improved selectivity to ethylene and propylene compared with the conventional microporous ZSM-5 and nano-sized ZSM-5. The enhanced performance is originated from the hierarchical structure and suitable acidity of the ZSM-5 microspheres.

ZSM‐5 zeolite incorporated flow battery membranes with regulated pore channels for high proton conduction

“…Figure 2C showed temperature‐programmed desorption of ammonia (NH 3 ‐TPD) curves of synthesized ZSM‐5 with different intensity of desorption peaks of NH 3 molecule at 190°C and 370°C. The increasing intensity of the desorption peak with the Si/Al ratio decrease indicated the addition of Brønsted acid site on the surface of ZSM‐5 20 . Combined with the results of x‐ray photoelectron spectroscopy (XPS) analysis and water contact angle test, it was also confirmed that the introduction of Al atoms enhanced the distribution density of the hydrophilic site on the surface of ZSM‐5 (Figures S4 and S5 and Table S1).…”

Hierarchical ZSM-5@SiO2 Catalysts: A Novel Approach to Optimizing Olefin Yield from Heavy Atmospheric Gas Oil

“…Therefore, in this study, a core−shell catalyst comprising ZSM-5 and amorphous-SiO 2 was developed to investigate the impact of steam treatment on the catalytic conversion of heavy atmospheric gas oil to light olefins. Steam treatment creates channels with extra mesopores in the parent zeolite, 12,23 facilitating the diffusion of larger molecules. 18,20 Alternatively, in the steam treatment of core−shell ZSM-5@amorphous-SiO 2 , the mesopores and micropores would perform differently than in parent ZSM-5.…”

“…Therefore, in this study, a core–shell catalyst comprising ZSM-5 and amorphous-SiO 2 was developed to investigate the impact of steam treatment on the catalytic conversion of heavy atmospheric gas oil to light olefins. Steam treatment creates channels with extra mesopores in the parent zeolite, , facilitating the diffusion of larger molecules. , Alternatively, in the steam treatment of core–shell ZSM-5@amorphous-SiO 2 , the mesopores and micropores would perform differently than in parent ZSM-5. In this study, hierarchical ZSM-5 with core–shell structures was utilized to investigate the catalytic reaction pathways at four different steam/oil ratios, along with their effects on propylene and ethylene selectivity during the conversion of heavy atmospheric gas to oil.…”

“…ZSM-5 has demonstrated high activity pertaining to the catalytic cracking of light hydrocarbon feedstock (pentane, hexane, and heptane) 10,11 as well as methanol-to-olefin conversion. 12 Several modifications are typically applied to the ZSM-5 zeolite component. Notably, metal impregnation has proven effective in assisting naphtha reformation, 13 showing potential as a catalyst for the dewaxing of gas oil.…”

MFI Type Zeolite Aggregates with Nanosized Particles via a Combination of Spray Drying and Steam-Assisted Crystallization (SAC) Techniques

“…Furthermore, only the conversion of aluminum-free nanosized zeolites was demonstrated, which have less relevance in catalysis and their hydrothermal syntheses already give high yields. Very recently, a strategy was demonstrated to produce hierarchical highly porous ZSM-5 microspheres by a combination of two processes: spray-freeze drying and steaming-assisted crystallization (SAC) [24,25].…”